Fair Value Measurements 1 (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions		Dec. 31, 2017	Mar. 31, 2017
Assets:
Foreign exchange derivatives	[1]	$ 8	$ 2
Total assets		1,071	1,079
Liabilities:
Foreign exchange derivatives	[1]	12	1
Total liabilities		12	1
Money Market Funds | Cash and Cash Equivalents
Assets:
Money market funds	[2]	1,063	1,077
Fair Value, Inputs, Level 1
Assets:
Foreign exchange derivatives		0	0
Total assets		1,063	1,077
Liabilities:
Foreign exchange derivatives		0	0
Total liabilities		0	0
Fair Value, Inputs, Level 1 | Money Market Funds | Cash and Cash Equivalents
Assets:
Money market funds	[2]	1,063	1,077
Fair Value, Inputs, Level 2
Assets:
Foreign exchange derivatives	[1]	8	2
Total assets		8	2
Liabilities:
Foreign exchange derivatives	[1]	12	1
Total liabilities		12	1
Fair Value, Inputs, Level 2 | Money Market Funds | Cash and Cash Equivalents
Assets:
Money market funds		0	0
Fair Value, Inputs, Level 3
Assets:
Total assets		0	0
Liabilities:
Total liabilities		$ 0	$ 0

[1] Refer to Note E, “Derivatives” for additional information.

[2] The Company’s investments in money market funds are classified as “Cash and cash equivalents” in its Condensed Consolidated Balance Sheets.